1. Fields of the Invention
The present invention relates to a driving device, and more particularly, to a driving device with a stepper motor wherein the rotation signal of a gear is sent to a sensing device to protect the stepper motor and the circuit board.
2. Descriptions of Related Art
Motors are used to transfer electric energy into mechanical energy which generates power to drive appliances which can be heavy equipment or small toys. Therefore are different types of motors and one of the motors that we use is the stepper motor which divides a full revolution into a number of equal steps so as to precisely control the positions and speed of the object or product that is cooperated with the stepper motor.
The conventional driving device using the stepper motor generally comprises a circuit board, a stepper motor, a gear reduction unit and an output gear, the circuit board controls the stepper motor to drive a product via the gear reduction unit and the output gear. The conventional driving device using the stepper motor is able to move the product up and down, or left and right.
One of the conventional driving device that moves the product up and down comprises a case in which a transmission driving device is received. The transmission device has a stepper motor, a driving gear, a passive gear and a shaft, wherein the stepper motor is connected with a worm rod and the driving gear is engaged with the worm rod. A transmission gear is connected beneath the driving gear, the passive gear is engaged with the transmission gear of the driving gear. The transmission gear has a threaded hole, the shaft has a threaded section which is threadedly extends through the threaded hole of the transmission gear. A notch is defined in one end of the shaft. The circuit board is connected to the transmission device and has a variable resistance that is slidably connected to the circuit board. The variable resistance has a movable guide rod which is engaged with the notch of the shaft. A cover is mounted to the case.
The driving device is used to adjust the headlight projection angle, thanks to the engagement between the gears, a less noise is generated and the transmission action is smooth and stable. However, the driving device adjusts the headlight is controlled by the stepper motor which is powered by the circuit board and drives the gears clockwise or counter clockwise. Nevertheless, there is not any response or feedback created from the gears so that even if the gears work under abnormal situations, the circuit board still drives the stepper motor. Therefore, the circuit board and the stepper motor may be damaged.
One of the conventional driving device that moves a window or door left and right comprises a case, a gear motor unit, a transmission rod unit and a rack, wherein the case receives the gear motor unit therein. A seat is connected to the case so as to be connected with a switch which is used to controls the manual switch function of the transmission rod unit. The gear motor unit comprises a motor and a gear reduction unit which is driven by the motor. The gear reduction unit has a first gear rod, at least one middle gear rod and a second gear rod, all of which are connected to each other by gears. The transmission rod unit has an upper socket connected to the seat so as to connect the transmission rod unit to the case. The upper socket has a room in one side thereof, and a hole is defined in the other side of the upper socket. The hole communicates with the room. A rear gear rod has a first engagement portion on one end thereof. One of the gears of the rear gear rod is engaged with the gear of the second gear rod. A clutch member has a second engagement portion so as to be engaged with the first engagement portion. A stop and a slot are located at one side of the clutch member and close to the second engagement portion. The stop is pushed by a guide face of the switch so as to move the clutch member. The other side of the clutch member is located in the room of the upper socket. The clutch member has a third engagement portion. A resilient member is biased between the rear gear rod and the clutch member. A front shaft has a fourth engagement portion at one end thereof so as to be engaged with the third engagement portion. A guide gear is pivotably connected to the front shaft and has a main gear. The rack is fixed to a dragging member so as to be engaged with the main gear.
Again, there is not any response or feedback created from the gears so that even if the gears work under abnormal situations, the circuit board still drives the motor. Therefore, the circuit board and the motor may be damaged.
The present invention intends to provide a driving device with a stepper motor to eliminate the shortcomings mentioned above.